ScriptLoader = function() {   
    this.timeout = 30;   
    this.scripts = [];   
    this.disableCaching = false;   
    this.loadMask = null;   
  };   
  
  ScriptLoader.prototype = {   
    showMask: function() {   
      if (!this.loadMask) {   
        this.loadMask = new Ext.LoadMask(Ext.getBody());   
        this.loadMask.show();   
      }   
    },   
  
    hideMask: function() {   
      if (this.loadMask) {   
        this.loadMask.hide();   
        this.loadMask = null;   
      }   
    },   
  
    processSuccess: function(response) {   
      this.scripts[response.argument.url] = true;   
      window.execScript ? window.execScript(response.responseText) : window.eval(response.responseText);   
      if (response.argument.options.scripts.length == 0) {   
        this.hideMask();   
      }   
      if (typeof response.argument.callback == 'function') {   
        response.argument.callback.call(response.argument.scope);   
      }   
    },   
  
    processFailure: function(response) {   
      this.hideMask();   
      Ext.MessageBox.show({title: 'Application Error', msg: 'Script library could not be loaded.', closable: false, icon: Ext.MessageBox.ERROR, minWidth: 200});   
      setTimeout(function() { Ext.MessageBox.hide(); }, 3000);   
    },   
  
    load: function(url, callback) {   
      var cfg, callerScope;   
      if (typeof url == 'object') { // must be config object   
          cfg = url;   
          url = cfg.url;   
          callback = callback || cfg.callback;   
          callerScope = cfg.scope;   
          if (typeof cfg.timeout != 'undefined') {   
            this.timeout = cfg.timeout;   
          }   
          if (typeof cfg.disableCaching != 'undefined') {   
            this.disableCaching = cfg.disableCaching;   
          }
      }   
  
      if (!url || this.scripts[url]) {   
        if (typeof callback == 'function') {   
          callback.call(callerScope || window);   
        }   
        return null;   
      }
      
      this.showMask();   
  
      Ext.Ajax.request({   
          url: url,   
          success: this.processSuccess,   
          failure: this.processFailure,   
          scope: this,   
          timeout: (this.timeout*1000),   
          disableCaching: this.disableCaching,   
          argument: {   
            'url': url,   
            'scope': callerScope || window,   
            'callback': callback,   
            'options': cfg   
          }   
      });   
    }   
  };   
  
  ScriptLoaderMgr = function() {   
    this.loader = new ScriptLoader();   
  
    this.load = function(o) {   
      if (!Ext.isArray(o.scripts)) {   
        o.scripts = [o.scripts];   
      }

      o.url = o.scripts.shift();   
  
      if (o.scripts.length == 0) {   
        this.loader.load(o);   
      } else {   
        o.scope = this;   
        this.loader.load(o, function() {   
          this.load(o);   
        });
      }
    };
  };
  
ScriptMgr = new ScriptLoaderMgr();